Dripping mercury circuit breaker

ABSTRACT

A circuit breaker for fluent electrical conductors, such as mercury, which consists of a chamber with a perforated plate at the top, a mercury and water inlet, a mercury outlet at the bottom and a water outlet located at an intermediate point. Mercury and water are introduced onto the perforated plate and are allowed to drip through the perforations into the chamber below. Electrical circuit through the mercury is broken when mercury is allowed to drip through the perforated plate in a discontinuous stream of drops. In the chamber, mercury being heavier than water, settles in a layer on the bottom, and water settles on the top of the mercury layer. Withdrawal of mercury is controlled by a trap in the mercury outlet line to maintain the desired level of mercury in the chamber. The method and apparatus can be used on single or multiple mercury streams and to break the amalgam circuit in a mercury amalgam denuder.

United States Patent Loftfield et a1.

[54] DRIPPING MERCURY CIRCUIT BREAKER [72] Inventors: Richard E. loftfield, Chardon; Warren R. Bailey, Painesville, both of Ohio; John C. Doolittle, Jr., Houston, Tex.

Oronflo De Nora Impianti Elettrochlmlci, S.A.A., Milan, Italy [22] Filed: Sept. 17,1969

[21] Appl.No.: 858,580

[73] Assignee:

[ 1 June 6, 1972 Primary Examiner-Winston A. Douglas Assistant Examiner-4i. A. Feeley Attorney-Hammond & Littell ABSTRACT A circuit breaker for fluent electrical conductors, such as mercury, which consists of a chamber with a perforated plate at the top, a mercury and water inlet, a mercury outlet at the bottom and a water outlet located at an intermediate point. Mercury and water are introduced onto the perforated plate and are allowed to drip through the perforations into the chamber below. Electrical circuit through the mercury is broken when mercury is allowed to drip through the perforated plate in a discontinuous stream of drops. in the chamber, mercury being heavier than water, settles in a layer on the bottom, and water settles on the top of the mercury layer. Withdrawal of mercury is controlled by a trap in the mercury outlet line to maintain 56] References Cited the desired level of mercury in the chamber. The method and apparatus can be used on single or multiple mercury streams UNITED STATES PATENTS and to break the amalgam circuit in a mercury amalgam denuder. 2,719,117 9/1955 Blue et al .,..204/27O 3,378,405 4/1968 Schumacher et al 1 36/86 A 11 Claims, 6 Drawing Figures WASH IATER ll LE T IECURY INLET I13" IATER OUTLET 1 DRIPPING MERCURY CIRCUIT BREAKER PRIOR ART The invention described herein can be used in connection with inclined or horizontal electrolytic cells and fuel cells. In the horizontal electrolytic mercury cell as described, for instance, in US. Pat. No. 2,544,138, mercury or mercury amalgam flows over the cell base from one end to the other forming a flowing mercury cathode. Anodes are disposed in spaced relationship above the flowing cathode, forming a gap therebetween. An electrolyte solution occupies the space between the anodes and the cathode, the level of which is usually well above the anodes. When an electric current is impressed, electrolysis of the electrolyte solution takes place. Horizontal mercury cells are normally operated at an inclination of the cathode base of about 0.25" from the horizontal, but may be operated with an inclination of between 0. 16 and 1.5 from the horizontal. The inclined mercury cells, which are similar in construction to the horizontal cells, are operated with an inclination of the cathode base, over which the mercury flows, of about 2 to about 85 from the horizontal, although the preferred inclination is the range of to 30.

For practical and design reasons, the inclined plane cells, such as described in US. Pat. No. 3,400,055, are constructed in tiers, i.e., one cell superimposed upon another. In such an arrangement, the base for the upper cell also serves as the top for the lower'cell, etc., and the anodes for the lower cell are attached to the underside of the base. Thus, the superimposed cells are arranged as bipolar cells wherein the upper side of the dividing base is the cathode contact and the lower side is the anode contact. In such an arrangement, the cell voltage drop for the different cells is the same, but the potential above ground for each cell is different. In operating a number of bipolar cells, there is a possibility of shorts formed by (1) the feed brine streams entering the bipolar elements, (2) the depleted brine streams leaving the bipolar elements, (3) the mercury streams entering the bipolar elements and (4) the amalgam streams leaving the bipolar elements. These shorts between the bipolar elements operating at different voltages result in current leakages, i.e., energy losses. The amount of current leakage is not a serious problem in the case of the brine streams because of the electrical resistance of the brine in the long conduits. However, the conductivity of the mercury and amalgam streams is so high that it poses serious problems, such as high current losses and mechanical damage to the cells. Shorts between the mercury streams at different voltages cause arcing and vaporization of the mercury with consequent health hazards and danger of explosions. For these reasons, it is necessary to take special precautions to handle the mercury and amalgam streams fed to the different tiers of a multiple tier bipolar cell so as to prevent the above problems.

The same problem also arises in the use of cells for the direct conversion of chemical energy into electrical energy, known as fuel cells, in which fluent mercury is used in the form of a sodium amalgam which flows through the cells. One type of a fuel cell is described in an article, Fuel Cells-State of the Art, 1961 by John I. Slaughter in Transactions of the Electrochemical Society, Indianapolis, Indiana, May 1, 1961. If several such cells are connected as bipolar cells, it is necessary to keep the amalgam in each cell electrically separated from that in each of the other cells. Likewise, in amalgam denuders receiving amalgam from electrolysis cells operating at different voltages, it is necessary to break the current between each cell of different voltage and the denuder chamber. 7

The device used to insulate a fluent conductor, such as mercury, in the tiers of the bipolar electrolytic cells or in fuel cell compartments is a circuit breaker. The prior art is replete with devices for breaking electrical current in fluent conductors. US. Pat. No. 3,400,055'disc1oses a star wheel circuit breaker used in conjunction with a two tier bipolar electrolytic cell. This circuit breaker is characterized by a pair of insulated star wheels rotatably mounted on a common horizontal shaft. Each star wheel is bounded at ends by circular plates and radial webs provide several compartments. Mercury for or from each tier is divided into individually separate increments when it flows through the compartments of the star wheels, thus breaking electrical circuit.

US. Pat. No. 3,324,020 describes a circuit breaker which includes a pair of concentric cylinders mounted for rotation on a common shaft. The concentric cylinders are provided with offset openings for discharging mercury into a reservoir. Mercury from an electrolysis cell enters the circuit breaker through a centrally disposed conduit which discharges mercury into the smaller of the two concentric cylinders. As the cylinders rotate in unison, mercury is eventually discharged through an opening into the larger of the two concentric cylindeis. In a similar manner, mercury is discharged from the larger of the two cylinders into the reservoir. Since the stream of mercury has been divided into separate increments, the electrical circuit through the mercury is thus effectively broken.

US. Pat. No. 3,324,020 makes a reference to other prior art circuit breakers of fluent conductors, i.e., US. Pat. No. 2,849,524, German Pat. No. 838,118 and Belgian Patent No. 482,217.

OBJECT S OF THE INVENTION It is an object of this invention to provide a method and apparatus for breaking electrical circuits in a fluent electrical conductor.

Another object of this invention is to provide a simplified method and apparatus for breaking electrical circuits in mercury and amalgam streams which are substantially free of moving parts and operate substantially automatically to break fluent electrical conductor streams.

Another object of this invention is the removal of solid particles, such as iron and nickel, from a stream of mercury thus enhancing cell operation by eliminating the formation of metal-mercury amalgams in electrolysis cells.

Another object of this invention is to strip sodium from a stream of mercury by mixing mercury with water and passing the mixture through a graphite decomposer chamber.

Another object of this invention is to break an electrical circuit in a stream of mercury and to sub-divide the main stream of mercury into a number of smaller streams.

Other objects and advantages of the invention will become apparent as description of illustrative embodiments, shown in the accompanying drawings, proceeds.

DESCRIPTION OF THE INVENTION This invention relates to a method and apparatus for breaking electrical current flowing through a fluent conductor. This invention is particularly adaptable to multiple tiered horizontal or inclined electrolytic cells, as well as to fuel cells and denuders having a flowing stream of mercury or mercury amalgam.

The function of the circuit breaker described herein, is to electrically insulate the individual streams of mercury in the electrolytic cell or a fuel cell from the main inlet and outlet streams, since the individual streams operate under different potentials and should not be mixed together unless the electrical charge is dissipated or the individual streams are adjusted to the same potential.

The circuit breaker essentially comprises a vessel with perforated plate at the top. Mercury and water are admitted onto the perforated plate and drop through the openings in the plate. Mercury and water are discharged through the openings in the form of a stream of discrete discontinuous drops which collect at the bottom of the vessel. The mercury drops, being heavier than water, settle to the bottom of the vessel and form a layer of mercury. The drops of water accumulate in a layer above the mercury. The vessel may handle single or multiple (separated) mercury streams.

An outlet for mercury is provided at the bottom of the vessel and an outlet for water is provided at a point intermediate the perforated plate and the mercury outlet. The mercury outlet is provided with a trap for controlling the level of mercury in the vessel. A baffle plate is secured at an angle within the vessel just above the mercury outlet for the purpose of halting the downward velocity of the mercury and to displace the mercury to one side and act as a trap to minimize water entrainment. A tube, attached to the baffle plate, is in communication with mercury below the baffle plate and the heterogeneous mixture of water and mercury, above. The tube functions as a vent or a recycle for any water which gets below the baffle plate. If excess water accumulates within the chamber, the pressure will force some of the water through the tube into the region of the heterogeneous water-mercury phase. A vent is provided at the top of the vessel for venting gases.

In another embodiment, especially suitable for the inlet side of a cell, a plurality of separate chambers, each fitted with a perforated plate at the top thereof, are provided in a vessel. Each of the chambers is similar to the embodiment described above, with the exception that a Weir box is mounted at the upper portion of the latter embodiment. Mercury and water inlets are provided in the weir box for supplying mercury and water from the weir box to the separate chambers. Mercury and water overflow from the weir box into the separate chambers over weirs cut in the wall of the vessel.

Another embodiment illustrates an application of the invention to multiple amalgam streams of different potential, feeding into an amalgam denuder.

For a more complete understanding of the invention, reference is made to the drawings, in which:

FIG. 1 is a cross-sectional view of a single circuit breaker;

FIG. 2 is a perspective view of an embodiment of a multiple stream circuit breaker;

FIG. 3 is a top view of the embodiment illustrated in FIG. 2;

FIG. 4 is a cross-sectional view along the plane 4 4 in FIG. 3;

FIG. 5 is a vertical cross-sectional view of a multiple stream circuit breaker coupled with an amalgam denuder, taken substantially along the line 5 5 of FIG. 6; and

FIG. 6 is a horizontal cross-section, taken along the line 6 6 of FIG. 5.

Referring to FIG. 1, circuit breaker 10 consists of cylinder 11 and top and bottom closure caps ,14, 16. Cylinder 11 may be a Pyrex glass cylinder, or metal or any other suitable material, with a side outlet .12 at approximately the mid-point of the cylinder. In the specific embodiment illustrated, the cylinder may be 6 inches ID, and 2 feet in length, although larger or smaller sizes may be" used depending upon the capacity required by the particular industrial installations. A closure cap 14 is mounted at the top of the vessel 10 and bottom closure cap 16 is fitted on the bottom thereof. Closure caps 14 and 16 are made of steel, although other materials may be used. The entire cylinder may be made of steel, or

glass, which will permit observation of what is taking place within the cylinder. Circumferential flanges 18 and 22 are provided integrally with closure caps 14 and 16. Pressure rings 20, 26 are also provided with flanges which are aligned with the circumferential flanges of the closure caps and secure the closure caps to the cylinder by means of nuts and bolts, shown in the drawing. To prevent leakage, rubber gasket rings 34, 36 are disposed between the contacting portions of the cylinder and the two closure caps. Rubber gasket ring 34, as well as the other gasket rings, may take the form of a putty seal. In case the cylinder is made of an electrically conducting material, insulating gaskets must be provided between the cylinder and the closure caps to break the electrical circuit running through iron, teflon, etc., and may be in the fonn of an expanded mesh openings in the perforated plate must be large enough to pass mercury and water through, but not so large that a continuous stream of water or mercury is formed, resulting in a continuous electrical path from top to bottom of the circuit breaker. Such a condition would defeat the purpose of a circuit breaker.

Mercury is introduced into the circuit breaker through inlet 38, and water through inlet 40. Once within the circuit breaker, water and mercury flow over the perforated plate 46, which may be a teflon disc, drilled with multiple holes and supported on an expanded mesh titanium support 460, and drop through the perforations in the plate into thechamber 48 below. The perforated plate 46 functions to breakup mercury and water into discrete particles or drops and thus break the electrical path through mercury. Once mercury and water clear the perforated plate, they are divided into drops that rain down and settle at the bottom of the circuit. Since mercury is heavier than water, a layer of mercury is formed on the bottom of the circuit breaker, with a layer of water above it.

Vent 42 is provided in the top closure cap for venting gases, and mercury outlet 44 is disposed at the bottom of the bottom closure cap. Mercury outlet is provided with a trap, not shown, to control the level of mercury in the circuit breaker and thus prevent entrainment of water in the mercury layer. Water is withdrawn from the circuit breaker through tee 50 secured in outlet 12 by means of stopper or other connection 52. Water flows through the arm of the tee directed downward, while the portion of the tee which is directed upward, serves as a vent for any entrained gases. in order to maintain perforated plate 46 in fluid-tight relationship, ring gasket 54 is positioned between the upper surface of plate 46 and the closure cap 14, while gasket- 34 is fitted on the underside thereof.

In order to dampen the impact of the falling mercury and reduce its velocity, plate 56 is mounted on an angle inside the lower portion of the circuit breaker. Bafile plate 56, being circular in this embodiment, is secured at an inclination to the wall of closure cap 16 just above outlet 44 and only partially obstructs the cross-sectional area of the vessel. A tube 58 provided with a bend 60 is affixed to the baffle plate 56 and extends vertically within the circuit breaker chamber. Bend 60 in the tube prevents mercury from entering the tube from the top, which could result in water entrainment in the mercury phase. Tube 58 is in communication with mercury disposed below baffle plate 56 and with the heterogeneous mercurywater phase above plate 56. When mercury descends into the lower portion of the circuit breaker, it encounters baffle plate 56. On impact, baffle plate 56 reduces velocity of the falling mercury and allows it to run down the incline and settle at the bottom of the chamber. When an excess of water is allowed to accumulate in the circuit breaker, the water is recirculated from below the plate 56 into the heterogeneous mercurywater phase above plate 56 by being forced through the tube 58.

In the dripping circuit breaker embodiment illustrated in FIGS. 2 4, a rectangular box is divided into two or more equal compartments 72, 74, 76, 78, 80. Each compartment is provided with a perforated plate 82, baffle plate 84, tube 86 and water and mercury outlets 88, 90, as in the embodiment shown in FIG. 1. Weir box 92 is secured to the back side of the circuit breaker and serves as a feed trough for mercury and water. Mercury is admitted to the weir box 92 through conduit 94 and inlet 96, and water through conduit 98 and inlet 100. Water and mercury overflow the weir box into the compartments over weirs 102, as is illustrated in FIG. 4.

The embodiment illustrated in FIGS. 2 4 may take the form of a cylindrical vessel sub-divided into circumferentially abutting segmented compartments, with the weir box located at the center thereof and weirs providing communication between each of the compartments and the weir box.

The embodiment shown in FIGS. 2 4 is especially adaptable to situations where it is desired to sub-divide a main steam into smaller streams which may be fed into different tiers of a multi-tier electrolysis or fuel cell, or where it is desired to feed an amalgam stream at difierent potentials into a denuder.

In the embodiment illustrated in FIGS. 5 and 6, a cylindrical amalgam denuder 103 having two or more insulated segmental amalgam receiving compartments 104, 105, 106, 107 and 108 receive sodium-mercury amalgam through the NaHg inlets 104a, 105a, 106a, etc., while water flows into the compartments 104 108 through water inlets 109. Water also flows into the denuder through inlets 110 and 111. Sodium hydroxide flows out of the denuder through outlet 112 and mercury, substantially stripped of its sodium content, flows out through the outlet 113.

In this embodiment of the invention, the amalgam entering the insulated compartments 104 108 and water entering inlets 109 drips through holes in perforated plate 114 made of teflon .or other suitable material and falls like rain drops through the water layer and water plus sodium hydroxide in compartment 115. In this compartment, the separated falling drops of mercury amalgam, indicated at 1 16, break all contact with the amalgam in compartments 104 108 and flow at a uniform potential through a perforated plate 117 into the denuder section 118 which is packed with graphite. In the denuder section, the mercury amalgam is substantially stripped of its sodium content and a layer of substantially pure mercury is formed in compartment 1 19 and flows out through outlet 113 for recycling to the process. Outlet 113 is provided with a gooseneck trap (not shown) to maintain the desired mercury level in compartment 119. The graphite particles are maintained in place between perforated plates 117 and 117a and may be further compressed when required by moving the shaft 120 downward under suitable pressure.

The sodium released in the denuder or decomposer section 118 forms sodium hydroxide with the water and releases hydrogen which is discharged from the outlet 12] and the dilute sodium hydroxide flows out through outlet 112. The water fed through water inlets 109, 110 and 111 can be regulated to control the amount of water in the decomposer and hot water may be fed to the inlets 109 to heat the mercury amalgam to the desired temperature. Water fed to inlets 109 also serves to wash the amalgam and keep the holes in plate 114 from plugging.

The dripping mercury circuit breaker described above serves the function of breaking the electrical path through the mercury by breaking up the mercury stream into discrete drops. The use of water in the circuit breaker is accompanied by a number of advantages. During mixing of water and mercury, water is effective in removing suspended particles, such as iron and nickel, from the mercury or amalgam which enhances cell operation by reducing metal-mercury amalgam or mercury butter formation in the cells. Since mercury has a tendency to vaporize at higher temperatures, the presence of water in the system reduces mercury vaporization.

Various modifications in the method and apparatus for breaking an electrical circuit through afluent electrical conductor may be made without departing from the spirit or scope of our invention.

We claim:

1. An apparatus for breaking electrical circuit through a fluent electrical conductor comprising a vessel, a perforated means disposed at the upper portion of said vessel, an inlet for the fluent electrical conductor disposed above said perforated means, an inlet for water above said perforated means, means for introducing the fluent electrical conductor and water onto said perforated means, and passing the fluent electrical conductor and water through said perforated means whereby the fluent electrical conductor is broken into discrete drops, thus breaking the electrical path through the conductor, outlet means at the bottom of said vessel to remove the fluent electrical conductor and wash water outlet means disposed above said fluent conductor outlet means in said vessel, means in said vessel to prevent entrainment of water in the fluent conductor layer and a baffle means secured in the lower portion of said vessel for dampening the impact of falling fluent conductor, said battle means only partially obstructing the crosssection of said vessel.

2. The apparatus of claim 1 wherein the fluent electrical conductor is a sodium-mercury amalgam and a vent is provided at the top of the vessel to remove gaseous reaction products. I

3. The apparatus of claim 1 wherein the fluent conductor is mercury and the perforated means is a perforated plate.

4. Apparatus of claim 1 wherein said baffle plate is secured at an incline above said mercury outlet, said apparatus further including a tube afiixed to said bafile plate for recirculating entrained water.

5. Apparatus of claim 4 wherein said tube includes a bend at its tip which has the function of preventing mercury from entering the tube from the top.

6. An apparatus for breaking an electrical circuit through a fluent electrical conductor comprising a vessel having in the upper portion a plurality of perforated means in compartments electrically insulated from one another and all of said compartments being connected to a weir box, inlet means for adding water to said weir box, inlet means for adding said fluent electrical conductor to said weir box, a common receiving compartment below said perforated means for receiving water and said fluent electrical conductor in discrete electrically separated compartment, bafile means partially obstructing the lower cross-section of said vessel to dampen the impact of the falling fluent conductor, outlet means in the lower portion of the vessel to remove said fluent electrical conductor and outlet means to remove water disposed above the fluent conductor outlet means.

7. The apparatus of claim 6 wherein the fluent electrical conductor is sodium-mercury amalgam and means to prevent entrainment of water in the mercury layer in the lower portion of the vessel.

8. An apparatus for breaking electrical current through a fluent electrical conductor comprising a four compartment vessel with perforated means separating the individual compartments, means for separately introducing water and fluent electrical conductor into the uppermost compartment, means for adding water to the second uppermost compartment, means for removing aqueous reaction products and means for removing gaseous reaction products from the second uppermost compartment, graphite packing in the third uppermost compartment, fluent electrical conductor outlet means in the bottom compartment and water inlet means in the bottom compartment above the fluent conductor outlet means whereby water passes through the perforated plate between the bottom compartment and the third uppermost compartment and through the graphite packing into the second uppermost chamber.

9. The apparatus of claim 8 wherein the uppermost compartment is divided into a plurality of insulated compartments, each provided with inlet means for fluent electrical conductor and water.

10. Apparatus of claim 6 wherein said means for introducing the conductor from said box to each of said compartments is a plurality of weirs provided in the wall separating said box and said compartments.

11. Apparatus of claim 6 wherein said bafile plate is disposed at an incline, and the number of said weirs corresponds to the number of said compartments, said apparatus further including a tube affixed to said baffle plate for recirculating water, and a regulating means in said mercury outlets for regulating the level of mercury in each of said compartments. 

1. An apparatus for breaking electrical circuit through a fluent electrical conductor comprising a vessel, a perforated means disposed at the upper portion of said vessel, an inlet for the fluent electrical conductor disposed above said perforated means, an inlet for water above said perforated means, means for introducing the fluent electrical conductor and water onto said perforated means, and passing the fluent electrical conductor and water through said perforated means whereby the fluent electrical conductor is broken into discrete drops, thus breaking the electrical path through the conductor, outlet means at the bottom of said vessel to remove the fluent electrical conductor and wash water outlet means disposed above said fluent conductor outlet means in said vessel, means in said vessel to prevent entrainment of water in the fluent conductor layer and a baffle means secured in the lower portion of said vessel for dampening the impact of falling fluent conductor, said baffle means only partially obstructing the cross-section of said vessel.
 2. The apparatus of claim 1 wherein the fluent electrical conductor is a sodium-mercury amalgam and a vent is provided at the top of the vessel to remove gaseous reaction products.
 3. The apparatus of claim 1 wherein the fluent conductor is mercury and the perforated means is a perforated plate.
 4. Apparatus of claim 1 wherein said baffle plate is secured at an incline above said mercury outlet, said apparatus further including a tube affixed to said baffle plate for recirculating entrained water.
 5. Apparatus of claim 4 wherein said tube includes a bend at its tip which has the function of preventing mercury from entering the tube from the top.
 6. An apparatus for breaking an electrical circuit through a fluent electrical conductor comprising a vessel having in the upper portion a plurality of perforated means in compartments electrically insulated from one another and all of said compartments being connected to a weir box, inlet means for adding water to said weir box, inlet means for adding said fluent electrical conductor to said weir box, a common receiving compartment below said perforated means for receiving water and said fluent electrical conductor in discrete electrically separated compartment, baffle means partially obstructing the lower cross-section of said vessel to dampen the impact of the falling fluent conductor, outlet means in the lower portion of the vessel to remove said fluent electrical conductor and outlet means to remove water disposed above the fluent conductor outlet means.
 7. The apparatus of claim 6 wherein the fluent electrical conductor is sodium-mercury amalgam and means to prevent entrainment of water in the mercury layer in the lower portion of the vessel.
 8. An apparatus for breaking electrical current through a fluent electrical conductor comprising a four compartment vessel with perforated means separating the individual compartments, means for separately introducing water and fluent electrical conductor into the uppermost compartment, means for adding water to the second uppermost compartment, means for removing aqueous reaction products and means for removing gaseous reaction products from the second uppermost compartment, graphite packing in the third uppermost compartment, fluent electrical conductor outlet means in the bottom compartment and water inlet means in the bottom compartment above the fluent conductor outlet means whereby water passes through the perforated plate between the bottom compartment and the third uppermost compartment and through the graphite packing into the second uppermost chamber.
 9. The apparatus of claim 8 wherein the uppermost compartment is divided into a plurality of insulated compartments, each provided with inlet means for fluent electrical conductor and water.
 10. Apparatus of claim 6 wherein said means for introducing the conductor from said box to each of said compartments is a plurality of weirs provided in the wall separating said box and said compartments.
 11. Apparatus of claim 6 wherein said baffle plate is disposed at an incline, and the number of said weirs corresponds to the number of said compartments, said apparatus further including a tube affixed to said baffle plate for recirculating water, and a regulating means in said mercury outlets for regulating the level of mercury in each of said compartments. 